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The following case may lead to the same system inode ref in confusion. A thread B thread ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode because of *arr == NULL, ocfs2_get_system_file_inode ->get_local_system_inode ->_ocfs2_get_system_file_inode gets first ref thru _ocfs2_get_system_file_inode, gets second ref thru igrab and set *arr = inode at the moment, B thread also gets two refs, so lead to one more inode ref. So add mutex lock to avoid multi thread set two inode ref once at the same time. Signed-off-by: jiangyiwen <jiangyiwen@huawei.com> Reviewed-by: Joseph Qi <joseph.qi@huawei.com> Cc: Joel Becker <jlbec@evilplan.org> Cc: Mark Fasheh <mfasheh@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
182 lines
4.7 KiB
C
182 lines
4.7 KiB
C
/* -*- mode: c; c-basic-offset: 8; -*-
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* vim: noexpandtab sw=8 ts=8 sts=0:
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*
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* sysfile.c
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*
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* Initialize, read, write, etc. system files.
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*
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* Copyright (C) 2002, 2004 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/fs.h>
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#include <linux/types.h>
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#include <linux/highmem.h>
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#include <cluster/masklog.h>
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#include "ocfs2.h"
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#include "alloc.h"
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#include "dir.h"
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#include "inode.h"
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#include "journal.h"
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#include "sysfile.h"
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#include "buffer_head_io.h"
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static struct inode * _ocfs2_get_system_file_inode(struct ocfs2_super *osb,
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int type,
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u32 slot);
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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static struct lock_class_key ocfs2_sysfile_cluster_lock_key[NUM_SYSTEM_INODES];
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#endif
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static inline int is_global_system_inode(int type)
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{
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return type >= OCFS2_FIRST_ONLINE_SYSTEM_INODE &&
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type <= OCFS2_LAST_GLOBAL_SYSTEM_INODE;
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}
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static struct inode **get_local_system_inode(struct ocfs2_super *osb,
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int type,
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u32 slot)
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{
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int index;
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struct inode **local_system_inodes, **free = NULL;
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BUG_ON(slot == OCFS2_INVALID_SLOT);
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BUG_ON(type < OCFS2_FIRST_LOCAL_SYSTEM_INODE ||
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type > OCFS2_LAST_LOCAL_SYSTEM_INODE);
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spin_lock(&osb->osb_lock);
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local_system_inodes = osb->local_system_inodes;
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spin_unlock(&osb->osb_lock);
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if (unlikely(!local_system_inodes)) {
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local_system_inodes = kzalloc(sizeof(struct inode *) *
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NUM_LOCAL_SYSTEM_INODES *
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osb->max_slots,
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GFP_NOFS);
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if (!local_system_inodes) {
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mlog_errno(-ENOMEM);
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/*
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* return NULL here so that ocfs2_get_sytem_file_inodes
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* will try to create an inode and use it. We will try
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* to initialize local_system_inodes next time.
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*/
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return NULL;
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}
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spin_lock(&osb->osb_lock);
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if (osb->local_system_inodes) {
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/* Someone has initialized it for us. */
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free = local_system_inodes;
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local_system_inodes = osb->local_system_inodes;
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} else
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osb->local_system_inodes = local_system_inodes;
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spin_unlock(&osb->osb_lock);
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kfree(free);
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}
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index = (slot * NUM_LOCAL_SYSTEM_INODES) +
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(type - OCFS2_FIRST_LOCAL_SYSTEM_INODE);
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return &local_system_inodes[index];
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}
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struct inode *ocfs2_get_system_file_inode(struct ocfs2_super *osb,
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int type,
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u32 slot)
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{
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struct inode *inode = NULL;
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struct inode **arr = NULL;
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/* avoid the lookup if cached in local system file array */
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if (is_global_system_inode(type)) {
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arr = &(osb->global_system_inodes[type]);
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} else
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arr = get_local_system_inode(osb, type, slot);
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mutex_lock(&osb->system_file_mutex);
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if (arr && ((inode = *arr) != NULL)) {
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/* get a ref in addition to the array ref */
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inode = igrab(inode);
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mutex_unlock(&osb->system_file_mutex);
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BUG_ON(!inode);
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return inode;
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}
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/* this gets one ref thru iget */
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inode = _ocfs2_get_system_file_inode(osb, type, slot);
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/* add one more if putting into array for first time */
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if (arr && inode) {
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*arr = igrab(inode);
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BUG_ON(!*arr);
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}
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mutex_unlock(&osb->system_file_mutex);
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return inode;
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}
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static struct inode * _ocfs2_get_system_file_inode(struct ocfs2_super *osb,
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int type,
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u32 slot)
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{
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char namebuf[40];
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struct inode *inode = NULL;
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u64 blkno;
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int status = 0;
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ocfs2_sprintf_system_inode_name(namebuf,
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sizeof(namebuf),
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type, slot);
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status = ocfs2_lookup_ino_from_name(osb->sys_root_inode, namebuf,
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strlen(namebuf), &blkno);
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if (status < 0) {
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goto bail;
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}
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inode = ocfs2_iget(osb, blkno, OCFS2_FI_FLAG_SYSFILE, type);
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if (IS_ERR(inode)) {
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mlog_errno(PTR_ERR(inode));
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inode = NULL;
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goto bail;
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}
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#ifdef CONFIG_DEBUG_LOCK_ALLOC
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if (type == LOCAL_USER_QUOTA_SYSTEM_INODE ||
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type == LOCAL_GROUP_QUOTA_SYSTEM_INODE ||
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type == JOURNAL_SYSTEM_INODE) {
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/* Ignore inode lock on these inodes as the lock does not
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* really belong to any process and lockdep cannot handle
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* that */
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OCFS2_I(inode)->ip_inode_lockres.l_lockdep_map.key = NULL;
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} else {
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lockdep_init_map(&OCFS2_I(inode)->ip_inode_lockres.
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l_lockdep_map,
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ocfs2_system_inodes[type].si_name,
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&ocfs2_sysfile_cluster_lock_key[type], 0);
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}
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#endif
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bail:
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return inode;
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}
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